www.mdpi.com/journal/ijerph Article Radioactive Iodide (131I−) Excretion Profiles in Response to Potassium Iodide (KI) and Ammonium Perchlorate

Abstract: Radioactive iodide (131I−) protection studies have focused primarily on the thyroid gland and disturbances in the hypothalamic-pituitary-thyroid axis. The objective of the current study was to establish 131I − urinary excretion profiles for saline, and the thyroid protectants, potassium iodide (KI) and ammonium perchlorate over a 75 hour time-course. Rats were administered 131I − and 3 hours later dosed with either saline, 30 mg/kg of NH4ClO4 or 30 mg/kg of KI. Urinalysis of the first 36 hours of the time-course revealed that NH4ClO4 treated animals excreted significantly more 131I − compared with KI and saline treatments. A second study followed the same protocol, but thyroxine (T4) was administered daily over a 3 day period. During the first 6–12 hour after 131I − dosing, rats administered NH4ClO4 excreted significantly more 131I − than the other treatment groups. T4 treatment resulted in increased retention of radioiodide in the thyroid gland 75 hour after 131I − administration. We speculate that the T4 treatment related reduction in serum TS